I don't think this is a MW bug. MAMEWAH doesn't sent the rompath for MAME (unless you configured it to). Perhaps you need to check your rom path in MAMEPP.INI?
Actually in my case it does, that's how I figured out the problem in the first place, by looking at the debug.log
I followed Stuzza's instructions from the link posted on the mamewah news page, and it says to set Send Rom Path to True, so I did.
I'll try it tonight with "Send Rom Path" to false.
By the way, I don't have a mamepp.ini either, I never bothered to run "mamepp -cc" since everything appeared to work fine without it.
Also while we're on the subject, what does "Use Long Filenames" do? Is it ignored for MAME? it doesn't seem to make a difference either way, and Stuzza's page says to set it to True in one place, and flase in another.
Stuzza, if you're monitoring this thread, maybe you can change your page to reflect this situation.
Cheers!